( 988)

(Referenced by 95)

We inserted White's gote-sente-combination of , , , in the hanezeki, which leaves Black behind in a grave dilemma.

is a suicidal ko-threat, so it is not available now. , and , are no valid ko-threats, because White's centre group has five liberties left. Black's ko-threats , and , in the nakade are compensated for by White's ko-threats , and , in the top left corner. This implies that Black cannot have occupied a shared liberty, at , but must have captured on the upper edge, instead. Another option would be that White did not capture the ko, but occupied a liberty, instead.

We consider Black's option first. captured the ko on the upper edge.

White's group has six liberties (w, 4 * c, m, Black's group has eight liberties (3 * b, 4 * c, k), so we are a bit early here.

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Black's group is above the Punishment Semeai Liberty Level, so Black's atari in the nakade is a valid ko-threat.

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Here also, White must use her own ko-threats in the top left corner.

Ko: ; ; ;

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Black's third ko-threat on the left side.

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After the exchange of for there are no valid ko-threats in the nakade any more. Therefore, Black is forced to connect the hanezeki's tail.

Ko: ; ; ;

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White has no "damage threatening" ko-threats left, but Black is unable to answer any of White's move on the left side locally.

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Black tries to protect his large group, but in vain.

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Black wins the semeai in the centre.

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But White's fourth move in a row kills Black's -group on the left side, so winning the game.

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We consider White's options now. Even if White waits a bit too long before capturing the ko for the first time, Black will not be able to win.

occupied a liberty of Black's group, and did not capture .

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Black cannot occupy a shared liberty, instead. Connecting the hanezeki's tail with a move at , instead, will result in a change in the order of moves.

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White can afford to occupy the last outside liberty of Black's group. In principle, White will capture the ko one move "too late" here, so we can expect that Black will not need the additional, external, ko-threat to win the ko-fight on the right side ( 965).

Ko:

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Black's ko-threats on the left side are compensated for ...

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... by White's ko-threats in the top left corner.

Ko: ;

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Black's last ko-threat on the left side.

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Black cannot afford to answer this atari locally.

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White's second move in a row on the left side.

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Black has no other ko-threats left but this suicidal one.

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White's third move in a row on the left side.

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As expected, Black wins the ko-fight. But this will no be sufficient to also win the game.

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White plays the fourth move in a row on the left side. Black's -group that looked so rock solid before has no option left to get two eyes. White will win the game.

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(Referenced by 352; 353)

Please note that inserting the exchange of , earlier would not have helped Black's group to escape its fate.

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White has the points to available for her four moves in a row, also killing Black's large -group on the left side.